View Full Version : 25y/o sub zero

12-13-2011, 07:15 PM
I am working on a 25 year old sub zero model number 3211 rfd. the customers complaint was no ice. i checked the temp of the freezer and it was 25 degrees f . not cold enough to produce ice. the compressor evap fan and cond fan where running. i then put my manifold gauges on the low side . no high side access valve. the running pressures were 10 psi on low side. i know that to achieve negative tempatures on an r-12 system my low side psi should be right around 3 to 5 psi. at this point im thinking either this thing is overcharged or has non condesibles in the system . just to see what happens i recovered some freon until my low side pressure was 4 psi. i told the customer to call me in 1 day and let me know if things have changed. they did not . i then evacuated the system and charged it with 11 oz of hot shot ( a r-12 drop in replacement. when i started charging the system the inside box temp was 72 degrees f by the time i left the customers house the box temp was 30 degrees 4 with a low side pressure of 5 to 6 psi. the custmer then called back and said still no ice and box temp was 28 degrees f . i checked all electrical the defrost timer turns the heater on and the defrost term takes is out , so there is no defrost hang up problem . all fans are running. the thermostat cycles on and off ( tested with heat gun) . the compressor does make a little bit of a noise( maybe valves) but my low side psi wasnt that high to indicate any discharge gas flowing back into the intake valve. at this point im a little thrown off by this thing. I am thinking about changing the liquid line dryers and blowing the cap tube out with nitrogen. and using either hot shot(r-12 drop in ) or r 409 to recharge. I have only been a tech for three years and am not that knowledgable when it comes to subzero . the customer knows he is going to have to invest some money into this unit so my question is should i even full around with changing the liquid line dryer or should i just replace the compressor to 134a and change the cap tube and liquid line dryer? the freshfood side system leaks aswell so i would probably just redo that side too . any advice or input would be great .

12-14-2011, 12:10 AM
sounds like a bad compressor. A clogged cap tube would result in low, not high pressure.

If you change the compressor, I would put in an R-12 compressor and charge it with an R-12 replacement.

12-17-2011, 12:05 AM
You might be suprised how much dust gets in the condensor coils on these.

04-07-2012, 09:24 PM
if this is a single compressor it's look like you okay and you condenser coil is clogged blowout your condensing coil you should have ice making at 25 it's look like your ice maker is not functioning make sure you have water in the ice maker






04-09-2012, 04:13 PM
when u charge with hot shot or 414 u lessen the charge by 20% not sure of the exact charge on that unit. don't go with 134. i think its a ae1410 with ab oil use that.

04-09-2012, 07:10 PM
If you pulled the charge you should have tapped the high side. I see no mention of high side pressure or temp of liquid line without all the facts we are basically guessing and not troubleshooting. I'd pulled charge, blow out cap tube, installed liquid line drier with high side access, Evacuate and then ReCharge with a R-12 replacement.